A great deal of research work has been conducted with the object of providing thermally stable, elastomeric polymers for various aerospace seal and sealant applications. To meet the rigid requirements for such applications, a polymer must also retain its elastomeric properties at sub-zero temperatures. Polymers that advance the art in meeting the requirements are disclosed by me in U.S. Pat. No. 3,846,376. Furthermore, in my copending U.S. application Ser. No. 610,474, filed on Sept. 4, 1975, and now issued as U.S. Pat. No. 3,994,861, thermally stable polymers are disclosed that retain their viscoelastic properties at temperatures even lower than do the polymers described in the aforementioned patent. While the polymers disclosed in the cited patent and patent application possess a broad use temperature range, they are often hydrolytically unstable upon exposure to humid conditions at elevated temperatures for extended periods of time. It would be very desirable to provide monomers that could be used to prepare polymers having a broad use temperature range that are also hydrolytically stable under severe conditions.
It is an object of this invention, therefore, to provide compounds that can be used as monomers in the synthesis of hydrolytically stable polymers having a broad use temperature range.
Another object of the invention is to provide a process for preparing perfluoroalkylene ether-imidate and -thioimidate ester monomers.
Other objects and advantages of the invention will become apparent to those skilled in the art upon consideration of the accompanying disclosure.